Error handling

Handling errors with Apollo

Any application, from simple to complex, can have its fair share of errors. It is important to handle these errors and when possible, report these errors back to your users for information. Using GraphQL brings a new set of possible errors from the actual GraphQL response itself. With that in mind, here are a few different types of errors:

GraphQL Errors: errors in the GraphQL results that can appear alongside successful data

Server Errors: server internal errors that prevent a successful response from being formed

Error policies

Much like fetchPolicy, errorPolicy allows you to control how GraphQL Errors from the server are sent to your UI code. By default, the error policy treats any GraphQL Errors as network errors and ends the request chain. It doesn't save any data in the cache, and renders your UI with the error prop to be an ApolloError. By changing this policy per request, you can adjust how GraphQL Errors are managed in the cache and your UI. The possible options for errorPolicy are:

none: This is the default policy to match how Apollo Client 1.0 worked. Any GraphQL Errors are treated the same as network errors and any data is ignored from the response.

ignore: Ignore allows you to read any data that is returned alongside GraphQL Errors, but doesn't save the errors or report them to your UI.

all: Using the all policy is the best way to notify your users of potential issues while still showing as much data as possible from your server. It saves both data and errors into the Apollo Cache so your UI can use them.

Any errors reported will come under an error prop along side the data returned from the cache or server.

Network Errors

When using Apollo Link, the ability to handle network errors is way more powerful. The best way to do this is to use the apollo-link-error to catch and handle server errors, network errors, and GraphQL errors. If you would like to combine with other links, see composing links.